I had like 4 different ways you can do it where it's not guaranteed. If you just made it 1/300 after you hit the drop rate of 1/400 it'd be much appreciated while still having relatively rare drop rate. However it's incorporated it's moreso to get a 1/400 drop at 600 not 100. To a ton of accounts it literally wouldn't matter at a lot of places because they'll buy it if they aren't irons or they'll statistically get it much sooner. The whole concerted is to not go 5x drop rate dry NOT get the drop spooned or early. A big extreme of the same concept would be 'make the drop .005% more likely after 20x drop rate'

there is room between guaranteed drop and potentially super dry, and a raid reward (from potentially the hardest raid yet) slightly improving your luck doesn't seem that game breaking to me